If You Want Rat Power For Your Tri-Five, One Of These Dart 540s Might Be Right Up Your Alley.

Our mild combo started out with a set of as-cast, 320cc Power Port heads from Trick Flow Specialties. Designed as a direct bolt on, the 320 cc aluminum heads offered 137 cc exhaust ports, 122cc combustion chambers and a 2.25/1.88 stainless steel valve combo. The impressive heads offered peak flow numbers of 362 cfm on the intake and 301 on the exhaust (measured at 0.800 lift), meaning our mild combo would not be taking full advantage of their ability to support well over 700 hp. The assembled heads even featured hydraulic roller valve springs (up to 0.700 lift), guide plates and 7/16 rocker arms. The heads were installed using Fel Pro 1017 head gaskets and ARP head studs.

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Working with the heads was a hydraulic roller cam and Weiand Team G single-plane intake manifold. For this mild combination, we chose an Xtreme Energy hydraulic roller cam and matching hydraulic roller lifters from Comp Cams. The XR288HR cam offered a 0.521/0.540 lift split, a 236/242 duration split (measured at 0.050) and a 110-degree lobe separation angle. Cam specs like this would be healthy on a small block or even a smaller displacement big-block, but 540 ci has a way of taming the cam considerably. The aggressive ramp rates offered by the Xtreme Energy line of cams was designed to maximize power production through the entire rev range.

This combo was completed with a Holley 950 Ultra HP carburetor, an MSD billet distributor and a set of 2.25-inch Hooker Super Comp headers. Additional components included an adjustable timing chain, Ultra Pro Magnum rockers and one-piece chrome-moly pushrods, all from Comp cams. Since we were running this on the engine dyno and not in a specific chassis, we chose a Pro Eliminator oil pan from Moroso.

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The Moroso pan featured a number of impressive features including an internal windage tray. Moroso also included one of its trick billet oil pumps. The billet pump featured larger inlet and oil passages to increase oil flow, reduced weight compared to a cast-iron pump (by 1 pound) and increased the mounting boss cross section to help spread the load. The integral bottom-fed design eliminated the need for an external oil pickup tube, the bypass system returned oil to the pickup area to reduce aeration and oil temperature and best of all the billet pump used the stock mounting stud and oil pump shaft. Use of the Moroso pan on a production Chevy block would require drilling and tapping the block for the revised mounting holes (inline with main caps-see photo), but our Dart block was already drilled and tapped for use with this pan.

The finishing touch was a two-piece timing cover from Comp Cams that allowed cam adjustments and swaps without dropping the oil pan (important when swapping components to our wild configuration).

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This version of our 540 was installed on the dyno with a pan full of Lucas 10W-40 oil and a tank full of pump gas. It was treated to a pair of computer-controlled break-in procedures lasting a total of 25 minutes. After a quick oil change, we were off and running. Some minor jetting on the Holley 950 Ultra HP carb was necessary and after running through a quick timing sweep to see where the engine made the best power, we were rewarded with peak power numbers of 635 hp and 646 lb-ft of torque. Though labeled mild in this instance, know that 635 hp would easily push your average Tri-Five well into the 11s, and possibly the 10s.

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To illustrate the strength and reliability of the impressive new Dart SHP short-blocks, we decided to subject one to a variety of different configurations ranging from mild to wild. Just for kicks, we even threw in a nitrous test.

The starting point for the 540 ci Special High Performance short-block was a Dart Big M Sportsman block.

Since we planned on running nitrous, we opted to upgrade the SHP short-block with a 4340 forged crank. All SHP BBC assemblies come with forged 4340 I-beam rods equipped with 7/16-inch cap screws.

Our 540 came equipped with forged flat-top pistons. Even with our increased displacement over a typical 454, the flat-top kept the static compression ratio down near or below 9.0:1. While this was perfect for our nitrous test (and superchargers at some point), it did reduce the power potential N/A.

The billet timing chain assembly from Comp cams allowed us to advance and retard the cam using an Allen-headed eccentric.

Working with the adjustable timing chain was a two-piece cover from Comp Cams. The two-piece design allowed us to swap cams without having to drop the Moroso oil pan.

Lubrication for our big-block was handled by a Moroso billet oil pump. The Moroso pump increased both volume and pressure to our 540 big-block. The pressure was rock solid during all of our testing.

The Moroso oil pump was covered with an aluminum Moroso oil pan. The oil pan featured an internal windage tray to improve power.

The Moroso oil pan featured revised mounting bolt locations adjacent to the main caps. Lucky for us, the Dart block came pre-drilled for use with this pan.

Here is the trick Moroso pan installed on the 540 and ready for testing. The pan sealed perfectly and certainly contributed to the impressive power numbers.

Headgear for our mild combo came from Trick Flow Specialties in the form of their as-cast 320 Power Port heads.

Though unported, (except the CNC entry) the as-cast 320cc intake ports offered impressive flow. With peak flow number over 360 cfm, these Trick Flow heads could easily support in excess of 700 hp on the right application.

The exhaust ports measured 137 cc and flowed a whopping 300cfm at 0.800 lift. Down near the 0.550 lift offered by our cam, the exhaust pots flowed near 255 cfm.

Sealing was courtesy of a set of Fel Pro 1017 head gaskets and ARP heads studs.

Comp Cams supplied a set of its trick new Ultra Pro Magnum roller rockers. The new design improved strength and increased valvespring and retainer clearance while simultaneously decreasing the mass of the rocker arm.

For induction chores, we installed a Weiand Team G intake. Given the displacement and torque potential of the 540, we chose the single-plane design over a dual-plane.

The Weiand Team G was topped off with a Holley 950 Ultra HP carburetor. The Ultra HP design featured a billet aluminum base plate, billet metering blocks and glass sight plugs.

We chose an MSD billet distributor for our Rat. The MSD ignition system also included a Digital 7 ignition amplifier.

Run on the engine dyno, the mild 540 Dart SHP motor produced peak numbers of 625 hp at 5,700 rpm and 646 lb-ft at 4,600 rpm. Torque production from the 540 exceeded 600 lb-ft from 3,300 rpm to 5,500 rpm.

The wild combination began with a set of Dart Pro 1 CNC heads. The Pro 1 335 heads offered exceptional flow characteristics to maximize power production.

As the name suggests, the Pro 1 335 heads featured 335cc intake ports. According to Dart, the 335 heads flowed nearly 400 cfm-enough to support over 800 hp on the right application.

The exhaust ports were also given the CNC treatment, to the tune of 129cc and peak flow numbers of 280 cfm (with the Dart-supplied exhaust valves).

Since we planned on stepping up in cam profile and timing, we chose a solid roller spring package. The Vasco-Jet springs offered a maximum lift of 0.790, 250 pounds of seat pressure and over 500 pounds of open pressure.

Out came the hydraulic roller can and lifters and in went the solid roller profile.

With the motor still warm from the previous test, off came the Trick Flow Power Port heads to make room for the Dart Pro 1s.

Our wild combination also required a suitable induction system. To maximize both power and visual appeal, we chose a Weiand Hi-Ram tunnel ram and a pair of 950 HP carburetors. Weiand also supplied the necessary dual-carb linkage.

Once everything was installed and tuned, the wild combo stepped up the power nicely with peak numbers of 777 hp at 6,600 rpm and 681 lb-ft at 5,600 rpm.

Though we had officially run the mild and wild combinations, we couldn't resist adding nitrous to the equation. To run our single plate system, we replaced the Weiand Hi-Ram tunnel ram with a Team G designed to accept a 4500 Dominator carb.

Since the big-block was already plenty powerful (especially given the 8.8:1 compression ratio), we needed a sizable amount of nitrous. We chose a Cheater Competition kit from NOS that allowed us to increase the power output of the 540 by a solid 250 hp. The NOS solenoids were installed on a custom nitrous mounting bracket from Wilson Manifolds.

Given the power output of the 540, we needed plenty of carburetor. Knowing this, we installed a 2-circuit Holley 1150 Dominator carburetor (part number 7320).

Prior to running the nitrous, we made a few baseline pulls with the Team G and Holley Dominator. Jetting was required to dial in the new induction system. Not quite as powerful as the tunnel ram, the 540 still produced 770 hp and 663 ft-lb with the single carb system.

The output of the NOS Cheater system was adjustable via jetting for the solenoids. We installed the 102/93 jet combination but eventually reduced the fuel jet down to 91 to dial in the air/fuel mixture (it was rich with the stock jetting).

Once everything was installed and tuned, the wild combo stepped up the power nicely with peak numbers of 777 hp at 6,600 rpm and 681 lb-ft at 5,600 rpm.

Mild vs. Wild 540
Equipped with the Trick Flow Power Port heads, mild XR288HR hydraulic roller cam and Weiand Team G intake, the 540 produced 635 hp and 645 lb-ft of torque. Stepping up to the dart Pro 1 heads, custom solid roller cam and Hi-Ram tunnel ram stepped the peak numbers up to 777 hp and 681 lb-ft of torque. As is evident, the wild version of the 540 shifted the torque curve significantly compared to the mild version. Where the mild 540 produce peak power at 5,700 rpm, the wild version did so at 6,600 rpm.

NA vs. NOS 540 (250 shot)
This graph illustrates the great thing about nitrous. It literally transformed the power curve at the touch of a button. After replacing the tunnel ram with a Weiand Team G and Holley Dominator carburetor, the 540 produced 770 hp and 663 lb-ft of torque. After some minor tuning with the 250hp shot, the NOS Cheater system upped these numbers to 1,022 hp and 839 lb-ft of torque. Note that we engaged the nitrous late in the rev range, but huge torque gains are available with earlier engagement.

We take Dart's largest big-block which happens to be a 540ci and build three combos that range from mild to wild and even a NOS build. Only at www.superchevy.com, the official website for Super Chevy Magazine. » Read More

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